In the field of decontamination of contaminated soils, various methods are known, microorganisms and, in some instances, nutrient solutions that promote the action of the microorganisms, typically being introduced into the earth. Thus, earth-working apparatuses, which include a cutter and agitator having angled vanes, are known from the German Patents DE 44 05 303 C1 and DE 195 29 439 C1, for example, it being a question of a specific vane configuration to obtain a desired comminution of the earth.
The vane configuration is selected to allow the earth picked up by the particular vane to be lifted due to the angular position thereof, crumbled, and to fall again behind the vanes, facilitated by a suitable free space provided therebetween. At the same time, underneath the vanes, a hollow space is formed in which the desired microorganisms, suspensions, nutrient solutions, granular material or the like can be introduced in a substantially unhindered manner through the outlet orifices located in the hollow shaft underneath the vane. The mentioned materials are also referred to as conditioning agents.
From the European Patent Specification EP 0 891 305 B1, a method is known for solidifying large quantities of pasty masses, such as sludge, marshy soil or tar, which provides for mixing at least one conditioning agent with the pasty masses. The method provides that the pasty masses located in a natural or artificial basin be set in motion on site within locally bounded regions, and that at least one conditioning agent be introduced while being simultaneously intermixed with the pasty mass, the conditioning agent being supplied directly to the work site from a storage tank located outside or inside of the basin. The conditioning agent is introduced by an earth-working apparatus underneath the surface of the pasty mass and is uniformly distributed both vertically, as well as horizontally, continuously over a predefined depth. In this case, the earth-moving apparatus is moved in the forward direction and orthogonally thereto.
In processes for conditioning tar lakes, for example, it turns out that the known earth-working apparatuses are used to effectively mix the tar with the conditioning agents in the area where the tar is in a dough-like state. However, over time, tar lakes, in the same way as other pasty masses, form a crust of greater or lesser hardness and thickness due to densification and drying-out processes at the surfaces thereof.
Upon penetration by an earth-working apparatus, this crust is broken up, thereby forming coarse clods on the one hand, and cracks and fractures in the immediate surrounding area. An undesirable and unintentional consequence is that the conditioning agent introduced under positive pressure can escape through these cracks up through the earth and thus contribute to environmental pollution. After removing and hauling away the contaminated material, it is then necessary to further condition the course clods at another location in order to treat and, in some instances, incinerate the material.